Some people keep their adult T's in critter keepers or 5 to 10 gallon tanks for adults for the ones you picked. So a 41 qt tub is over kill IMO. 12 qt to 15 qt is better.

There are good caresheets for them but I am on my phone at the moment.

You could have them in tubswithout lids if they are in a rack. You could also use the tub itself with the lid on it and secure the lid down if you wanted.

Yes you could keep them in a rack. Generaly no heat is required unless the room gets really cold then back heat could be used but you need to be careful.